package com.example.flink.wc;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.functions.KeySelector;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.KeyedStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.util.Collector;
//DataStream实现wordCount：读文件（有界流）
public class StreamWordCountExample {

    public static void main(String[] args) throws Exception {
        //  1.创建环境
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        //  2.读取文件
        DataStreamSource<String> lineDS = env.readTextFile("input/words.txt");

        //  3.处理数据：切分、转换、分组、聚合
        SingleOutputStreamOperator<Tuple2<String, Integer>> wordAndOne = lineDS.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
            @Override
            public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
                //  3.1 切分数据、转换
                String[] words = value.split(" ");
                for (String word : words) {
                    // 转换成二元组(word,1)
                    Tuple2<String, Integer> wordsAndOne = Tuple2.of(word, 1);
                    // 通过Collector发送给下游
                    out.collect(wordsAndOne);
                }
            }
        });

        //   3.2 分组
        KeyedStream<Tuple2<String, Integer>, String> wordAndOneKS = wordAndOne.keyBy(new KeySelector<Tuple2<String, Integer>, String>() {
            @Override
            public String getKey(Tuple2<String, Integer> value) throws Exception {
                return value.f0;
            }
        });

        //  3.3 聚合
        SingleOutputStreamOperator<Tuple2<String, Integer>> sum = wordAndOneKS.sum(1);

        //  4.打印
        sum.print();

        //   5.执行
        env.execute();
    }

}
